Capsaicin induces ferroptosis via suppression of SLC7A11 activity and upregulation of ACSL4 mediated by AMPK in tongue squamous cell carcinoma

Qiwei Zhao¹Yu Wang¹Long Ding¹Zhuang Li¹Mengyang Wang²Yueqing Huang²Qiushi Cao¹Yaqin Sun¹Xiaohong Guo^1*

• ¹Hubei Shizhen Laboratory, Hubei University of Chinese Medicine, Wuhan, China
• ²Hubei University of Chinese Medicine, Wuhan, Hubei Province, China

Global incidence of tongue squamous cell carcinoma (TSCC) has been steadily increasing. Our previous studies have demonstrated that capsaicin (CAP) can promote apoptosis and inhibit cell migration, thereby exerting anti-TSCC effects. Here, we aimed to validate whether CAP has the potential to induce ferroptosis in TSCC and to reveal the related mechanisms. CCK-8 results showed that CAP suppressed the cell viability of HN6 and CAL27. Observations by Transmission electron microscopy (TEM) showed the mitochondrial structure was damaged after CAP treatment.Moreover, levels of malondialdehyde (MDA), Fe 2+ and reactive oxygen species (ROS) were all increased while the level of glutathione (GSH) was decreased. However, these effects could be reversed by ferroptosis inhibitor ferrostatin-1 (Fer-1), which suggested that ferroptosis was induced by CAP. Western blot results showed that CAP significantly increased the expression of phosphorylation of AMP-activated protein kinase (AMPK) and acyl-CoA synthetase long chain family member 4 (ACSL4) and reduced the expression of glutathione peroxidase 4 (GPX4). Furthermore, we found that CAP inhibited the release of glutamate and enhanced the binding of BECN1 and solute carrier family 7 member 11 (SLC7A11), indicating a reduction in the activity of SLC7A11 through the AMPK/BECN1 pathway. The expression of p-BECN1 and ACSL4, along with the alterations in MDA, Fe 2+ , GSH, and ROS, indicated that the inhibition of AMPK can partially alleviate the ferroptosis induced by CAP, which was further confirmed in vivo. In conclusion, our study demonstrates that CAP activate the AMPK signaling, inhibits the activity of SLC7A11 and increases ACSL4 expression, thereby inducing ferroptosis in TSCC.